Electron
An electron is a fundamental subatomic particle with a negative electric charge, found in atoms and responsible for electricity and chemical bonding.
How big is it?
9.109 × 10⁻³¹ kg · mass
Mass · measured constant
A little perspective
Electron vs Proton: mass comparison
A proton has about 1,840 times the mass of an electron.
An electron is a fundamental subatomic particle with a negative electric charge, found in atoms and responsible for electricity and chemical bonding.
A proton is a positively charged particle found in the nucleus of atoms, made up of quarks.
Bar length measures mass, not physical size. Both bars start at zero kilograms (kg). Pictures identify the objects only.
Measurements, assumptions & sources +
Electron
Mass: 9.109 × 10⁻³¹ kg; measured constant.
The length shown is the electron Compton wavelength, not its diameter. In the Standard Model the electron is treated as pointlike; the cloud is a schematic.
NIST — 2022 CODATA fundamental constants
The marked mass is calibrated. Unmeasured illustration details are representative.
Proton
Mass: 1.673 × 10⁻²⁷ kg; measured constant.
Twice the approximately 0.8409 fm charge radius. The charge distribution has no hard boundary; the illustration is schematic.
NIST — 2022 CODATA fundamental constants
The marked mass is calibrated. Unmeasured illustration details are representative.
Use the visual comparison to explore its scale, then check the measurements and sources.
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Why this measurement?
Why we use 9.109 × 10⁻³¹ kg
We compare the mass of an electron. This is a measured value; check the notes for its source and scope.
The length shown is the electron Compton wavelength, not its diameter. In the Standard Model the electron is treated as pointlike; the cloud is a schematic.
The picture identifies the subject; the diagram compares the recorded values. How calibrated comparisons work →
Recorded properties
Dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 9.109 × 10⁻³¹ kg | Not recorded | measured constant | |
| 2.426 pm | Not recorded | measured constant |
Around this scale
Explore nearby values.
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Sources and method
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The source records and measurement method remain available for inspection.
- NIST — 2022 CODATA fundamental constantsRecommended constants with uncertainties; exact SI definitions are distinguished from measured constants.
More ways to see it
Curated comparisons
There’s always another scale
Follow your curiosity.
Fundamental physicsPlanck length1.616 × 10⁻³⁵ mThe Planck length is a scale formed from fundamental physical constants.
MicroscopicHydrogen atom105.8 pmA hydrogen atom is the simplest neutral atom, with one proton in its nucleus and one electron around it.
MicroscopicDNA double helix2 nmDNA is the molecule that stores hereditary information in living organisms.
Fundamental physicsProton1.682 fmA proton is a positively charged particle found in the nucleus of atoms, made up of quarks.
Fundamental physicsNeutron1.675 × 10⁻²⁷ kgA neutron is a type of subatomic particle found in atomic nuclei, carrying no electric charge and playing a key role in holding nuclei together.
MicroscopicWater molecule280 pmA water molecule is a group of two hydrogen atoms bonded to one oxygen atom.
MicroscopicGlucose molecule1 nmA glucose molecule is a simple sugar used by living cells as a source of chemical energy.
MicroscopicVirus100 nmA virus is an infectious particle containing genetic material inside a protein coat, sometimes with an outer envelope.